Electrical Measurement Standards for Electric Vehicle Charging

The expansion of electricity as a zero-emission transportation fuel in California requires the development of a reliable network of publicly accessible commercial charging stations capable of safe and accurate fueling of electric vehicles. Prior to full-scale commercialization, devices used in commercial transactions must undergo type evaluation testing to assure that the measuring device is accurate; repeatable; designed to operate in the conditions it will be exposed to; cannot be used to defraud customers and communicates a fair and accurate accounting of all measurements and charges to the customer. For type evaluation to occur, there must be enforceable standards in the form of tolerances and specifications for the device in question. Prior to establishing tolerances and specifications, there must be established primary reference standards to which a device can be tested and compared to. Electric vehicle supply equipment is experiencing a strong expansion into commercialization, device specifications and tolerances, and test procedures need to be fully developed to support an equitable and consistent marketplace that fosters adoption of zero emission vehicle technology. The California Department of Food and Agriculture, Division of Measurement Standards is responsible for the establishment and oversight of specifications and tolerances for commercial weighing and measuring devices in the state. The Department of Measurement Standards State Metrology Laboratory maintains the standards of measurement: length; mass; time; volume; temperature; and alternating current electrical power used to ensure that all devices provide accurate and traceable measurements for their respective units of measure. A primary standard is needed with the operating range necessary for calibrating and testing electric vehicle supply equipment measurements to traceable and known values for both alternating current and direct current power. Field standards used to test installed equipment on-site that is calibrated to the primary standard are needed to support and maintain a reliable and robust statewide commercial electric vehicle fueling network. Finally, specifications and tolerances for electric vehicle supply equipment developed by the National Conference on Weights and Measures must be adopted for successful commercialization of the electric vehicle fueling market.